Blasting machine



July 2.9, 1930. c. P. BANzHoF 1,771,870

BLASTING MACHINE Filed Aug. 5, 1929 2 Sheets-Sheet 1 20 j; J9 H l; y

July 1930. c. P. BANzHoF 1,771,870

BLASTING MACHINE Filed Aug. 5, 1929 2 sheets-'sheet 2 Patented `luly 29, 1930 UNITED STATES PATENTI OFFICE CHARLES P. BANZHOF, OF LANCASTER, PENNSYLVANIA, ASSIGNOR OF THREE-FOURTHS TO THE FIDELITY IILIxlC'lRICv COMPANY, OF LANCASTER, PENNSXLVANIA, A COR- POBAIION OF PENNSYLVANIA BLASTING MACHINE Application filed August 5, 1929. Serial No. 383,588.

This invention relates to electric generators of the class for setting off blasting charges and aims to provide an improved hand-operable machine for instantaneously generating the high-power current necessary to fire a plurality of charges simultaneously as well as successive or single charges.

Another important object is to provide a simple and durable machine of smallest possible size and weight for convenience in considerably in electric characteristic, a uniform firing thereof is dependent upon the heating of a small bridge-wire or e uivalent by passing a current therethrough or igniting the fulminate surrounding it.

In arrangement for firing, the caps are generally connected in series so that the same amount of current passes through each. If one of the series is more sensitive than the others and the current is not high enough to fire all the caps together, the more sensitive one is likely to fire and open the circuit so as to prevent the remaining caps from firing. On the other hand, if one in the series requires a higher firing current than the others, it may fail to fire and explode its charge. Said failures constitute a grave danger and great precaution is necessary to uard against workmen being injured by acci ental ignition of unfired charges in the dbris of multiple blasts. I`

These caps moreover have an inherent time lag, i. e., they do not fire instantly as the current isapplied but momentarily await heating of the bridge-wire. This timelag varies inversely with the magnitude of the current, from which it follows that sufficiently high current will reduce the lag to a zero point and all caps in the series will be fired simultaneously. Therefore, if a current of double or more the normal firing requisite is forced through the circuit, every cap will heat and fire with only the remotest possibility of failure.

From the foregoing it will be appreciated that a current generator or blasting machine for firing the caps must have definite operative characteristics rendering it instantaneously productive of a high magnitude current, and the purpose of this invention is to provide such a machine.

The invention will be best understood from further description with reference to the attached drawings wherein a machine of one practical embodiment thereof is illustrated.

In said drawings:

Fig. l is a sectional viewof the machine from one side;

Fig. 2 represents a plan view as taken on the line 2 2 of the first figure;

Fig. 3 is a transverse section on the line 3 8 of the first figure;

Fig. 4 is a plan section on the line 4-4 of said first figure;

Fig. 5 is a curve-chart representing apprpximate values of output and generation ra e;

Figs. 6 and 7 are charts representing current values attained respectively with the ordinary armature and the armature of the present machine; and l Fig. 8 is a diagram of the machine circuit and its connections with charge detonators or caps.

The illustrative machine is shown fitted into a metal casing 8 having a removable cover 8a secured thereto but permitting easy access to the component parts.

This machine comprises a body member 9 in the form of a frame carrying the other parts and providing the main field or magnet of thev generating plant. vSaid member or frame isformed of a material having high permeability which also will retain a relatively high residual magnetism, such for example as the well known product of iron with relatively high content of ferrie-carbide, In this instance the material is composed of a the ferrie-carbide content being commercially controlled b permitting rapid cooling after molding. uch material is used for said frame because it is found to have the particularly appropriate characteristic of retaining considerable magnetism (by virtue of the hi h ferrie-carbide content) forming the basis or a quick building up of current, which is essential to the attainment of a high I current output in machines of this kind where Vrates of excitation or E. vM. F.-

the operativecycle by hand impulse is so short. This feature coupled with the fact that the high component of graphitized carbon in the iron gives the material the additional characteristic of high permeability,

I v makes it es ecially appropriate to this use.

The buil ing up o magnetic flux in the lield of this ma et is accelerated by a proper will give a high total flux resulting in high current generation, due as aforesaid to the high retentive and permeability characteristics of the material comprising the ole pieces and yoke of the field member. his is an im ortant feature of the invention.

n the chart of Fig. the approximate eneration with fields of high and low residual magnetism are re resented for the purpose of comparison. n this figure the line X is the voltage curve of the new type of field forming a part of this invention and the line Y is the voltage curve of a field retaining only a small amount of residual magnetism.

Between yoke portions at one end of the aforesaid frame is an armature" on a shaft 11 and carrying a commutator 12.V This arma-v ture and its commutator are preferably of six segment or six-partform for the purpose of producing current of more sustainedvalue than vis possible with the ordinary two-part j commutator. The diierence in current production between the ordinary -twolpart commutatorjand the six-partcom'inutator used in the present machine jis illustrated by the curves in Figs. Gand -7 from which it will'be,

` seen that not'onlyis a more sustained current vvalue to be derived from the six-part commutator and armature divisions, but there is the 'added'advantage of increased current tened to the frame and having extensions 'l f carrying brushes 14 within insulated holders on opposite sides of the commutator.

The upper end of the amature shaft is shown journaled in a nonmagnetic housin member 15 fastened to the upper end of the rame.

Uniting the side portions of the frame at its other end is a field magnet core 9 around which are series field windings 17 and shunt field windings 18. These windings, which accelerate the building up of magnetic flux as above stated are connected in an electrical circuit including the commutator, conductors 19 and 20, current output terminals 21 and a closure switch, as represented in Fig. 8.

Said terminalsare carried on a non-'conductive bridge 22 within the aforesaid housing member 15. One of these terminals in this instance forms part of the aforesaid closure switch comprising flexible contact arms 21* and 21b insulated from each other and adapted to close the circuit therethrough on being hrou ht in contact. To this one of the termina s, the conductor 19 including the series windings is connected, while the conductor including the shunt windings connects withthe other. `Restin firmly in contact with these terminals are inder posts 23 carried by the casing cover for convenience in connecting themachine with the detonating circuit. This connection is represented in the aforesaid Fig. 8 wherein 24 indicates the blasting caps.

Projecting upwardly from the housing 15 is a rotary spindle 25 having bayonet joint .connection withan operating handle 26. This splirhxlle lcarries a segmental gear 27 which 'ts rotation in opposite directions byabutment against opposite sides of a lu or shoulder portion 15l of the housing. Sai gear carries an insulated pin 27 to engage behind and liex one arm of the closure switch against the other as the gear approaches'its rotation limit in the direction indicated by the arrow in Fig. 2. The reason for placing the pin at this point will be hereinafter explained. Said gear remains normally in the position shown in Fig. 2 and is returned to suchdposition by a spring 28 actingon its spin e. H

Engaging with-'the segmental gear is a pinf ion 29 idling on ashaft 30 journaled inthe housing memberf Keyed to said shaft is a full gear 31 carrying a spring tensioned awl 32 en aging the aforesaid pinion toloc lthe gear or rotation therewith in onedirection while allowing independent movement in the other. v Thus when the segmental ar is moved from normal position, its rotation will be im arted in opposite direction to the full geart rough the pinion locked therewith by i the pawl, but when the segmental gear is ar-l rested or vreturned to normal position, the

pawl simply ratchets over the pinion and permits continued rotation of the full gear.

Said .full gearen ages with a pinion 33 4 on the armature sha to im art rotation to said armature. This multi e gear arrangement will obviously cause high speed rotation i of the armature when the spindle is turned manually by its handle and its ls ed will be even greater under vigorous im u se. Ahigli vorder to secure themaximum output of the machine. The relation of factors to this condition may be representedA by the equation l5 @grs-HF,` where M represents the of the.

armature, S the speed of rotation, T the time or duration of the-power impulse and F theI force or power required to complete the stroke. As the factors T and F are determinable'and virtually fixed by the strength of the operator, M and S are the only quantities to be taken as variable and since it is desirable that S shall be as high as ssible, it naturally follows that M must be ept as low as possible. To secure this condition, the multiple gear arrangementis made in such ratio and the armature is so proportioned in weight and diameter that the averagp operator will be able tov impart a very hi speed thereto within the limited extent an duration of the machines power stroke. A high magnitude current is accordingly ilgenerated almost iiistaneously through the eld windings.

As the segmental gear nears its limit of stroke, the in 27 thereon as previously stated engages be ind and iiexes one arm of the closure switch' against the other to complete the 1 circuit. The switch is thus caused to close bewhatfI c aim as new and desire to secure by'.A Letters Patent of the United States is LA 'elvqtri gvnerawrv'vf the class defore the segmental gear has completed its stroke for two important reasons, fir is desirable to close the cap circuit be ore the end of the ower stroke soas to send out and maintain t e high current volume in the circuit while continuing its ture opening of the circuit b any rebound or tendency of the o erator to raw back before completing the fu impulse stroke.

' f From the foregoing it will be appreciatui Ithat thisfinvention rovides a greatly` improved and exceeding y powerful machine in s ite of its small size, whereby tiring-of all etoiiators in -a blasting circuit attached will be assured. Y

' As numerous modifications with changes in form and arrangement of arts may obviously'be made without departing from the spirit and scope of the invention, the appended *claimsl are not intended to limit the same to the specic construction shown.- f

. Havin "thus described core; a multi-part commute tatable inthe eld of said magnetya handthat it turnable spindle carryin a. segmental gearl neration v in the v machine, and second, that it prevents premamy invention, l

.output controlling switch-member connected 'l in circuit with the armature,

coil and actuated t0 close Just before t e endA scribed comprising in combinatiomla Vmagnet `of a material of high permeability and retentive of relatively high residual magnetism having a portion thereof providing a core; f

series and shunt eld energizing windings around said core; a multiart commutated armature rotatable inthe eld of saidmagnet; a hand-turnable spindle carryin a se plying gearing forfquickly imparting highspeed rotation to said armature with movement in one direction of limited stroke; and a' normally open switch-member connected in a current-output circuit with said` windings and armature, said switch-member` being acl tuated to close by an element on the aforesaid `gear before the latter reaches the end ofits power stroke.

,mental gear in association with a spee -multi- 2. An' electric generator of thel classlvdescribed embodying a ma terial of high permeability and retentive of et body of a marelatively high residual magnetism having a portion thereof providin a core; series energizing windings aroun said core; a shunt excitation coil; a multiart commutated armature rotatable in the eld of said ma net; and a current-'output controllin' switc member connectedin circuitwith tl e armature, windings and coil which'is closed just before the end of a short power stroke givingl high-speed impulse to said armature.

' 3. An electric generator embodying in lcombination, a body member of a material having high permeability and retentive of relatively hig Vresidual magnetism forming the main field magnet and having a portion thereof providing a magnetjcore; series and shunt Held energizing windi s around said 'armature roin association with spee -multiplying gearingr'for quickly impartin high-speed rotation tol said armature wit 'movement in-one direction of limited stroke; and ya normally 4. An electric generator yof 'the class described embodyinga body member of a maj terial ,o high permeability and, retentive of Y-relativel high residualmagnetism having a core wit energizing windings anda shunt excitation coil a multi-part commutated armature rotatable' inthe field of -said magnet, means including speed-multiplying gear-- ing for imparting h1 h-speed rotation to said armature so as to bui d up a high volume current in a'minimui'n of time, and alcurrent-f .110'A open switch-member connected in a currentv voutput circuit withgsaid windings andarmeture, said switch-member being actuated vto `'close just before .the aforesaid .gear'reaches' vthe end of Aits power stroke giving impulse Vv"iis y -to said armature.

the

of an applied power stroke giving impulse to said armature.

5. An electric generator of the class described comprising in combination. a main lield magnet formed of a material ot high permeability and retentive ot relatively high residual magnetism subject to a high degree of induction, said magnet having a portion providing a core; series and shunt field en ergizing windings around said core; a multipart conimutated armature rotatable in the tield of said magnet; a normally open switchmember and current-output terminals connected in circuit with said windings and armature; together with hand-operated means including a segmental gear with associated speed-multiplying gearing for quickly imparting high-speed rotation to said armature with limited movement in one direction so as to build up a high magnitude current in a minimum of time by the magnetizing forces, said segmental gear Jfunctioning to close the switch-member just be fore it reaches the end of its impulse stroke.

6. In an electric generating machine of the character described including energizing windings and a shunt excitationA coil with multi-part commutated armature and closure-switch in a current-output circuit; a main tield magnet having a core around which said winding and coil are wound the one upon the other, said magnet being .formed of a material having the characteristics of high permeability and retentive of relatively high residual magnetism subject to a high degree of induction accelerated by the shunt coil.

7. In an electric generating machine of the character described including energizing windings and a shunt excitation coil with multi-part commutated armature and clo-l sure-switch in a current-output circuit; a main field magnet having a core around which said winding and coil are wound the one upon the other, said magnet being formed of a material such as iron with relatively high ferrie-carbide content characterized by its high permeability and retentive of relatively high residual magnetism making it subject to a high degree of induction.

8. An electric generator comprising in combination a magnet body formed with a core1 saidfbody being of a material of high permeability and retentive of relatively high residual magnetism subject to a high degree of induction; a series energizing coil and a shunt coil wound one upon the other around said core; a multi-part commutated armature rotatable in the tield of the magnet body to induce a current of'high and evenly sustained value in a minimum ot' time; a normally open switch-member and current-output terminals connected in circuit with said coils and a'rmature; together with means including a segmental gear and associated speed-multiplying gearing for imparting high-speed rota- CHARLES P. BANzHoF. 

